A TROPICAL WAVE IS OVER THE E TROPICAL ATLC WITH AXIS E OF THE CAPE
VERDE ISLANDS NEAR 20W. CIRA LAYER PRECIPITABLE WATER IMAGERY
SHOW MODERATE MOISTURE ASSOCIATED WITH THE WAVE FROM THE SURFACE
TO 850 MB MAINLY IN ITS W AND S ENVIRONMENT WHERE SUPPORT
SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS FROM 05N TO 10N
E OF 25W.

Satellite data indicate that the area of low pressure over the
tropical eastern Atlantic has acquired sufficient organization to be
classified as a tropical depression. The low-level center appears
embedded beneath a relatively small cluster of deep convection, but
convective banding is also increasing to the west and north. The
initial intensity is set at 25 kt based on Dvorak estimates from
TAFB and SAB and recent ASCAT data.

The depression is located near the southwestern edge of a mid-level
anticyclone, giving the cyclone an initial motion of 285/8 kt. The
anticyclone is expected to move westward in tandem with the
depression over the next couple of days, keeping it on a general
west-northwestward track for much of the forecast period. By days 4
and 5, however, there is significant uncertainty in the track
forecast. The GFS and GFDL show the cyclone feeling the influence
of an amplifying deep-layer trough over the eastern Atlantic, which
turns the depression northward. The ECMWF and UKMET, on the other
hand, keep the ridge as the dominant influence and continue a
west-northwestward motion. Due to the large spread in the guidance,
the official forecast shows the cyclone slowing down considerably by
days 4 and 5, and is a little west of the model consensus aids at
those times.

The environment looks conducive for at least gradual strengthening
during the forecast period. Sea surface temperatures are warm,
vertical shear should remain generally low, and environmental
moisture patterns appear favorable for at least the next two days.
Beyond 48 hours, most of the global models show the cyclone
threading the needle beneath a narrow upper-level ridge, with
mid-level dry air possibly getting into the western part of the
cyclone's circulation. This pattern makes the intensity forecast
complicated because hostile upper-level winds won't be too far away,
and the ultimate strength of the cyclone will depend heavily on its
eventual track. For now, the NHC official forecast shows only
gradual strengthening through day 4, more or less in line with the
SHIPS and LGEM guidance.

The depression's cloud pattern has been increasing in organization.
A primarily convective band over the eastern half of the circulation
has been increasing in curvature and the cloud tops are cooling
significantly. The initial wind speed is increased to 35 kt in
agreement with the latest CI numbers from TAFB and SAB and UW-CIMSS
ADT value.

Westerly shear associated with an upper-level trough, extending
from the eastern subtropical Atlantic into the eastern Caribbean,
could increase over Ida during the next day or so and slow the
cyclone's rate of intensification. Global models agree that a
relative reduction in the shear should occur in 2 to 3 days when a
piece of the upper-level trough cuts off near the Greater Antilles,
which could allow Ida to strengthen, perhaps even more than
forecast. Late in the forecast period, the uncertainty in the
intensity forecast increases considerably, with the ECMWF calling
for more northwesterly shear and less favorable thermodynamic
variables in the storm's environment than in the GFS. The new
intensity forecast is only slightly higher than the previous one
through 72 hours. The forecast after that time is of low confidence
and essentially levels Ida's intensity off in agreement with the
SHIPS model output.

Recent fixes suggest that the cyclone's motion has been more
northwesterly (or 305/06) since earlier today. Ida is being steered
by east-southeasterly to southeasterly flow underneath a subtropical
ridge migrating westward with the cyclone, and some increase in
forward speed is predicted by the models during the next day or so.
In about 48 hours, a deep-layer trough amplifying southwestward
across the eastern Atlantic will cause steering currents surrounding
Ida to collapse, which should result in the cyclone's forward motion
coming to a halt. With increasing northerly or northwesterly flow
aloft, Ida should begin to meander in about 4 days and even
drift southward or southeastward by day 5. The new track forecast
is adjusted to the right some throughout the period, primarily due
to the more northwesterly initial motion but also in the direction
of the multi-model consensus.

Ida has been producing a large cluster of very deep convection
overnight and this morning. The tropical cyclone, however, is still
being affected by shear as the low-level center can be seen in
visible satellite imagery just northwest of the convection, and this
was confirmed by a recent scatterometer pass. The initial wind speed
is maintained at 45 kt, which is based on the latest TAFB Dvorak
T-number and the recent ASCAT data that revealed winds of around
40 kt.

The upper-level wind pattern is forecast to become a little more
conducive for strengthening during the next 12 to 24 hours and the
NHC forecast calls for some slight intensification. After that
time, northwesterly shear is expected to increase as an upper-level
trough to the northeast of Ida retrogrades westward. This could
cause some weakening, but most of the intensity guidance shows
little change in strength during this time, and the NHC forecast
maintains an intensity of 55 kt from 24 to 72 hours. Later in the
forecast period, the global models take the upper-level trough
northeastward and develop a more favorable upper-air pattern over
the tropical cyclone, which should allow for strengthening by
days 4 and 5. The new NHC intensity forecast is similar to the
previous advisory, and is close to the SHIPS and LGEM
models.

The forward motion of Ida continues to decrease and is now 330/6
kt. The steering currents around the tropical cyclone are forecast
to further weaken during the next day or so as the mid- to
upper-level trough retrogrades westward. Ida should become
nearly stationary tonight, then meander eastward or east-
southeastward on Tuesday and Wednesday as the mid- to upper-level
flow becomes northwestward. The dynamical models have come into
better agreement on this scenario, including the latest GFS run
that shifted eastward and is now close to the ECMWF. After 72
hours, when the trough moves northeastward, Ida should turn
northwestward at a faster forward speed. The updated NHC
track has been adjusted eastward and is close to a blend of the
ECMWF, GFS, and GFS ensemble mean.

A LARGE AREA OF CLOUDINESS CONTINUES OVER THE CENTRAL ATLANTIC
ASSOCIATED WITH A 1009 MB SURFACE LOW...REMNANTS OF
IDA...CENTERED NEAR 25N58W AND ITS ASSOCIATED FRONTAL TROUGH
EXTENDING FROM THE LOW TO 23N52W. THIS SYSTEM HAS BECOME A
BETTER ORGANIZED SINCE YESTERDAY AND ADDITIONAL DEVELOPMENT IS
EXPECTED DURING THE NEXT SEVERAL DAYS WHILE IT MOVES NW.
SCATTERED MODERATE CONVECTION IS OBSERVED FROM 24N-30N BETWEEN
46W-63W. THE CHANCE OF FORMATION OVER THE NEXT 48 HOURS IS
MEDIUM.